Cathode ray deflection apparatus



Jan. 1119,1939. E RusKA 7' "2,1435% QATHODE RAY DEFLECTION APPARATUS Filed May 20, 1936 Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE signor to the firm of Fernseh Aktiengesellschaft, Zehlendorf, near Berlin, Germany Application May 20,

1936, Serial No. 80,887

In Germany May 23, 1935 Claims.

The present invention relates to cathode ray tubes in which cross deflection of the electron ray is used.

Magnetic cross-fields produced by coils are fre- 5 quently used for deflecting corpuscular rays, particularly electron rays, from their starting position. The magnetic flux produced in the coils unites together outside so as to surround the tubes. The path of the magnetic flux has a magnetic resistance, to overcome which, the current windings of the coil are utilized. By guiding the magnetic flux (which, as recited joins onto itself exteriorly of the coils) back by means of and within ferromagnetic materials, the magnetic resistance of this portion of the path may be appreciably decreased and the number of ampere turns of the coils thus correspondingly reduced, Hitherto such coils were wound on ferromagnetic cores which, in the form of double coils such as are generally used for deflecting purposes, were connected together in magnetic conducting relation by means of a common yoke.

The feature of this known magnetic short circuit is that the coils are wound around the ferromagnetic core.

It has been proposed, in lieu of two separate deflecting coils used for deflecting in one coordinate direction, to use a single coil having windings of interconnected cross section and which intersects the deflected ray. In accordance with the present invention such coils are surrounded by a ferromagnetic jacket which is closed to the greatest extent possible, and which takes up the magnetic flux prevailing exteriorly of the coil. The

feature of this new type of magnetic short circuit is that the coil windings in this case are completely disposed inside the ferromagnetic material.

In the drawing,

Fig. 1 is a phantom perspective View, partly in section, of a preferred embodiment of my invention.

Fig. 2 is a diagram, showing how my invention is mounted in a cathode ray tube.

The ferromagnetic jacket I is provided with corresponding openings 2 and 3 at the places where the ray passes. If one or two crossed coils 4 are used for ray deflection purposes and these have rectangular or trapezoidal cross sections, the casing has the shape of a square or a rectangular truncated pyramid section provided with a round hole 2 on the ray inlet side (the smaller side of the rectangle in the case of a truncated section of a pyramid) and a slit-shaped or rectangular hole 3 in the ray outlet side (bottom plate of the 5 pyramid) which if desired may embody the size relationship of the controlled television image. In the drawing, for purposes of clarity, only one coil is shown. A deflecting system of the type described combines greatest deflectional sensitivity with least inductivity. The jacket according to the invention effects a further increase of sensitivity and at the same time produces great homogeneity of the fleld inside the coils. This is of appreciable technical advantage in all deflecting systems, especially however, for those of high frequency, as in the case of the Braun type of television receiving and transmitting tubes. In order to utilize these advantages to the fullest extent, the material of the jacket should be free from hysteresis and of a loss-less nature, these being properties which are possessed for example by a granulated ferromagnetic material possessing but slight magnetic loss characteristics, e. g. Sirufer, which comprises finely granulated iron with a shellac or artificial resin binder.

I claim:

1. In combination with a cathode ray oscillograph tube having means for producing an undeflected ray, ray-deflecting means comprising a closed ferromagnetic jacket, having end apertures axially formed therethrough, disposed within said tube symmetrically about said undeflected ray, and deflecting coils disposed within said jacket symmetrically about said undeflected ray.

2. In combination with a cathode ray tube arranged to produce an undeflected cathode ray, ray-deflecting means comprising a closed ferromagnetic jacket positioned within said tube symmetrically about said undeflected ray and having the form of a parallel-ended truncated pyramid, apertures disposed centrally through said parallel end portions, cross-deflecting coils disposed symmetrically within said jacket, said jacket being so positioned and arranged within said tube that said apertures and deflecting coils are symmetrical about said undeflected ray.

3. In combination with a cathode ray tube arranged to produce an undeflected cathode ray, ray-deflecting means comprising a ferromagnetic jacket positioned within said tube symmetrically about said undeflected ray and of truncated pyramidal form, parallel ferromagnetic end portions formed on said jacket, apertures centrally disposed through said end portions, cross-deflecting coils disposed within said jacket, said jacket being so positioned and arranged within said tube that said apertures and deflecting coils are disposed symmetrically about said undeflected ray.

4. In combination with a cathode ray tube arranged to produce an undeflected cathode ray,

from the source of said undefiected ray, said aperture being symmetrically disposed about said undeflected ray, and deflecting coils positioned within said jacket.

5. A deflecting coil system for a cathode ray tube substantially as described in claim 4, having the magnetic field closing means for said coils disposed within the said cathode ray tube.

ERNST RUSKA. 

